#include <bits/stdc++.h>

using namespace std;

uint64_t sumOfGroup(int64_t k) {
    // Return the sum of the elements of the k'th group.
    uint64_t p=k*(k-1)/2;
    p=p*2+1;
    uint64_t sum=0;
    while(k>0){
        sum+=p;
        p+=2;
        k--;
    }
    return sum;
}

int main() {
    uint64_t k;
    cin >> k;
    uint64_t answer = sumOfGroup(k);
    cout << answer << endl;
    return 0;
}